Fullerene-Graphene Acceptor Drives Ultrafast Carrier Dynamics for Sustainable CdS Photocatalytic Hydrogen Evolution

Ultrafast excited-state decay and intrinsic charge carrier recombination restrain the photoactivity enhancement for solar-to-H-2 production. Here, a CdS-fullerene/graphene (CdS-F/G) photocatalyst is synthesized for enhancing visible-light-driven hydrogen generation from earth-abundant water. The CdS-F/G shows ultrafast interfacial electrons/holes transfer and holes self-trapping process in photocatalysis. The in-situ dynamic study from transient absorption spectroscopy reveals the sub-microsecond-lived excited states (approximate to 172.6 ns), interfacial electron transfer (approximate to 30.3 ps), and hole trapping (approximate to 44.0 ps) in the CdS-F/G photocatalyst. The efficient active species transportation and prolonged lifetime significantly enhance the charge separation state survival, increasing the photoactivity and photostability. Consequently, visible-light activity enhancement (>400%) of H-2 evolution reaction (HER) is obtained at the CdS-F/G photocatalyst with high stability (>36 h). The 127.2 mu mol h(-1) g(-1) performance corresponding to a quantum efficiency of 7.24% at 420 nm is not only higher than the case of pristine CdS (29.2 mu mol h(-1) g(-1)) but also much higher than that of CdS-Pt photocatalyst (73.8 mu mol h(-1) g(-1)). The cost-effective CdS-F/G photocatalyst exhibits a great potential for sustainable and high-efficiency photocatalytic water splitting into clean energy carriers. Moreover, the optimized electronic structure associated with interfacial electrons/holes transfer and holes self-trapping promotes overall water splitting for H-2 and O-2 generation.

Automated summary

Ultrafast excited-state decay and intrinsic charge carrier recombination restrain the enhancement of photoactivity for solar-to-H-2 production. A CdS-F/G photocatalyst is synthesized for visible-light-driven hydrogen generation, demonstrating ultrafast interfacial charge transfer and self-trapping process. In-situ dynamic study reveals sub-microsecond-lived excited states, interfacial electron transfer, and hole trapping, enhancing charge separation and increasing photoactivity. The CdS-F/G photocatalyst exhibits high stability and achieves a quantum efficiency of 7.24% at 420 nm.